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In this study, under the conformity of engineering reality, considering the influence of slip coefficient on the variation range of winding angle, 15 composite lay‐up schemes of hydrogen storage vessels were designed using grid theory, and the hydrogen storage vessels's structural strength was analyzed. The distribution of non‐geodesic fiber windings on the outer surface of the inner layer was solved using differential theory and the winding principle, and ABAQUS established the finite element model. The maximum stress value and stress distribution of the composite layer of the hydrogen storage vessel along the fiber direction were studied, the damage of the composite layer was analyzed, and the pressure and mode of the bursting were predicted. Results show that the structural strength of the hydrogen storage vessel designed by this method can be effectively guaranteed. The hoop winding layer bears the majority of the stress on the hydrogen storage vessel, while the helical winding layer's fiber strength is not entirely utilized. The hydrogen storage vessel gains greater structural strength when the circumferential winding layer is concentrated and situated at the outermost portion of the composite layer. The layup scheme has an impact of approximately 17.21% on burst pressure. Highlights: Effect of slip coefficient on the change of winding angle.Different forms of composite lay‐up schemes were designed.The stress distribution in the composite layer was studied.Analyzed structural strength and damage of the composite layer.Predicted the pressure and mode of bursting. [ABSTRACT FROM AUTHOR]

The continuous increase in the operating speed of rail vehicles demands higher requirements for passive safety protection and lightweight design. This paper focuses on an energy-absorbing component (circular tubes) at the end of a train. Thin-walled carbon fiber-reinforced polymer (CFRP) tubes were prepared using the filament winding process. Through a combination of sled impact tests and finite element simulations, the effects of a chamfered trigger (Tube I) and embedded trigger (Tube II) on the impact response and crashworthiness of the structure were investigated. The results showed that both triggering methods led to the progressive end failure of the tubes. Tube I exhibited a mean crush force (MCF) of 891.89 kN and specific energy absorption (SEA) of 38.69 kJ/kg. In comparison, the MCF and SEA of Tube II decreased by 21.2% and 21.9%, respectively. The reason for this reduction is that the presence of the embedded trigger in Tube II restricts the expansion of the inner plies (plies 4 to 6), thereby affecting the overall energy absorption mechanism. Based on the validated finite element model, a modeling strategy study was conducted, including the failure parameters (DFAILT/DFAILC), the friction coefficient, and the interfacial strength. It was found that the prediction results are significantly influenced by modeling methods. Specifically, as the interfacial strength decreases, the tube wall is more prone to circumferential cracking or overall buckling under axial impact. [ABSTRACT FROM AUTHOR]

Highlights Hydrogen‐fueled vehicles, recognized for their environmental benefits as they emit only water vapor, represent a sustainable alternative to traditional cars. This paper investigates the relationship between the microstructure and mechanical properties of carbon fiber‐reinforced epoxy composites used to manufacture lightweight hydrogen storage pressure vessels through the filament winding process. This fabrication technique, while common, often results in variable fiber orientations and porosity content that affect the mechanical properties of the composite structures. Our study uses tubes made from carbon fiber reinforced epoxy resin with different angular fiber orientations (±15° and ±30°) and multilayer structures to analyze how these variations impact the mechanical properties and damage behavior of the composites. A series of tests, including physical–chemical characterizations, porosity measurements, and multiscale mechanical assessments such as tensile and loading‐unloading analysis have been conducted. The results demonstrate that porosity, measured in the range of 5%–7%, significantly impacts mechanical performance. Moreover, a 40% decrease in Young's modulus was observed between the ±15° and ±30° fiber orientations, and a 65% reduction was noted for the multilayer structure. Microscopically, the presence of porosity initiates cracks and leads to fiber/matrix decohesion and fiber breakage. Mesoscopically, these defects can merge to form transverse cracks and micro‐delaminations between layers, highlighting the complex behaviors of these composites under loading. This information is critical for improving the design and durability of hydrogen storage systems. Porosity, measured in the range of 5%–7%, significantly affects mechanical performance, reducing Young's modulus by up to 40% between ±15° and ±30° fiber orientations and by 65% in multilayer structures. Fiber/matrix decohesion and crack initiation due to porosity lead to the formation of transverse cracks and micro‐delaminations between layers, affecting the durability of the composite. Optimizing fiber orientation and reducing porosity are critical to improving the mechanical performance and long‐term durability of hydrogen storage vessels. [ABSTRACT FROM AUTHOR]

In this study, the post‐buckling damage behavior of cylindrical composite tubes was examined experimentally. The samples were reinforced with glass, carbon, and kevlar fibers to obtain glass‐reinforced fiber polymer (GRFP), carbon‐reinforced fiber polymer (CRFP), and Kevlar‐reinforced fiber polymer (KRFP) cylindrical tubes. The samples were produced using 4 stacking layers with filament winding technology. In producing all composite tubes, the outer diameter was kept constant at 17 mm, and two inner diameters of 12 and 13 mm, two wall thicknesses, 5 winding angles, and two lengths were used as parameters. The load was applied to the samples until completely damaged, and the maximum post‐buckling load values obtained were measured on the testing device. The effect of different reinforcement materials, winding angle, wall thickness, and length on the load‐carrying capacity was analyzed and it was understood that they had a significant effect. It was observed that the load‐carrying capacity of GFRP samples was the highest compared to the others, followed by CFRP and KFRP samples, respectively. In all samples, it was observed that a 0.5 mm wall thickness increase increased the load‐carrying capacity, while a 50 mm length increase decreased it. The energy absorption (EA) values of GFRP, CFRP, and KFRP samples were 46.99, 25.22, and 15.48 Joules, respectively. It was understood that the energy absorption of GFRP samples was 1.86 times better than CFRP and 3 times better than KFRP. Highlights: The samples were produced using the fiber winding method, which is one of the most common production methods in the manufacture of tubes.Three different polymer reinforcement materials were used in the production of the samples.The effects of polymer reinforcement material, winding angle, length, and wall thickness on the maximum post‐buckling load were investigated.Wall thickness was found to have a significant effect on the maximum post‐buckling load.It was observed that GFRP samples had the highest energy absorption feature. [ABSTRACT FROM AUTHOR]

Although it is seen in the literature that composite pipes are produced by filament winding, there are limited number of studies on the use of fabric wrapping and autoclave. In this study, in order to fill this gap and contribute to the literature and industry, composite pipes were produced using fabric wrapping and autoclave methods together and their mechanical and thermal properties were investigated. The effect of carbon nanotube (CNT) reinforcement on these properties was also investigated. According to low velocity impact (LVI) test, 10%–25% impact strength increase was observed with CNT reinforcement. Thermogravimetric analysis (TGA) shows that mass loss decreased by ⁓10% and the degree of thermal degradation increased by ⁓10%. In dynamic mechanical analysis (DMA), it is observed that epoxy glass transition temperature (Tg) increased by 11% with CNT reinforcement. At the end of the study, the mechanical and thermal properties of the pipes produced by autoclave and fabric wrapping methods were improved compared to the literature and contributed to science and therefore to the increased use of prepreg carbon pipes in the industry. Highlights: Composite carbon pipes were produced by applying prepreg fabric wrapping and autoclave curing methods together.The mechanical and thermal properties of multi‐walled carbon nanotube (MWCNT) reinforced and unreinforced carbon composite pipes were investigated.According to TGA, it was observed that the mass loss decreased.Thermal decomposition temperature increased for MWCNT reinforced and unreinforced samples.According to DMA, Tg of epoxy decreased for MWCNT unreinforced sample and increased for MWCNT reinforced sample. [ABSTRACT FROM AUTHOR]

A liquid oxygen-compatible epoxy resin of fluorinated glycidyl amine (TFEPA) with a low viscosity of 260 mPa·s in a wide range of temperatures, from room temperature to 150 °C, was synthesized and used to decrease the viscosity of phosphorus-containing bisphenol F epoxy resins. And the forming process and application performances of this resin system and its composite were investigated. The viscosity of the bisphenol F resin was decreased from 4925 to 749 mPa·s at 45 °C by mixing with 10 wt.% TFEPA, which was enough for the filament winding process. Moreover, the processing temperature and time windows were increased by 73% and 186%, respectively. After crosslinking, the liquid oxygen compatibility was preserved, and its tensile strength, elastic modulus, and breaking elongation at −196 °C were 133.31 MPa, 6.59 GPa, and 2.36%, respectively, which were similar to those without TFEPA. And the flexural strength and modulus were 276.14 MPa and 7.29 GPa, respectively, increasing by 21.73% in strain energy at flexural breaking, indicating an enhanced toughness derived from TFEPA. Based on this resin system, the flexural strength and toughness of its composite at −196 °C were 862.73 MPa and 6.88 MJ/m3, respectively, increasing by 4.46% and 10.79%, respectively. [ABSTRACT FROM AUTHOR]

This investigation reveals the reasons behind severe shear distortion of carbon fiber towpreg observed during a series of winding sequences involving a geometry consisting of a hyperbolic hyperboloid attached to two cylinders at its open sides. The roving severely distorts at the transition zones, tending to slip and lose track, while the robust winding machine undergoes noticeable and unexpected vibrations. The DO IT 2 root cause analysis problem-solving method is applied to understand the failure mechanism using flow and causal diagrams, along with CNC data analysis. The winding angle at geometric transitions is measured using photographs. Additional data analysis involves evaluating the limits of mathematical functions used to construct the mandrel meridian profile, along with analyzing winder kinematics. The results reported here reveal numerical singularities that adversely affect solutions at all levels by impacting the mathematical definition of the meridian profile. This explains the shear-type distortion of the towpreg, speed changes surpassing ISO 10816-1 standards on mechanical vibration, alongside peaks in acceleration and jerk. Moreover, it is suggested that Coulomb's friction law may surpass its limits due to a viscous and tacky interface promoted by the non-rigid nature of the stranded towpreg. Preventive actions involve meeting the requirements of the Theory of Curves and Surfaces for mandrel meridian profile construction. Additionally, incorporating observed viscoelastic and shear strength phenomena into theoretical approaches is advised, alongside addressing discrepancies in measuring the filament winding angle and validating numerical solutions against CNC data. [ABSTRACT FROM AUTHOR]

Drawing upon both theoretical and experimental methodologies, this study investigates the vibrational characteristics of lattice sandwich truncated conical shells featuring composite ribs made of carbon and E-glass fibers. Toward this aim, the equations of motion along with the corresponding boundary conditions of such sandwich shells are derived using classical Donnell's shell theory and the smeared stiffness technique. Subsequently, the governing equations are solved to obtain a closed-form expression for natural frequencies employing the Galerkin method. In addition, ABAQUS simulations are presented to study the vibration behavior of single-skin and three-skin conical shells. To validate the theoretical methods, the specimens of three-layer sandwich conical shells were fabricated from two Kevlar fabric laminates and a composite lattice core with hexagonal cells using a manual filament winding process. The composite ribs consist of carbon and E-glass fibers with a ratio of 3:1. Finally, experimental modal tests were conducted to extract natural frequencies and mode shapes by measuring frequency responses at 40 points over a duration of 60 s using a laser vibrometer. A strong correspondence is observed between the theoretical outcomes (utilizing the Galerkin and FE methods) and the experimental findings (with a maximum discrepancy of approximately 16% for the initial four mode shapes). Findings indicate that the excellent performance of the composite lattice core in vibration behavior, which can increase approximately 19% and 16% the natural frequencies corresponding to the first and second mode shapes, respectively. [ABSTRACT FROM AUTHOR]

Currently, there is limited research on the in situ forming process of thermoplastic prepreg tape winding, and the unclear impact of process parameters on mechanical properties during manufacturing is becoming increasingly prominent. The study aimed to investigate the influence of process parameters on the mechanical properties of thermoplastic composite materials (CFRP) using laser-assisted CF/PPS winding forming technology. The melting point and decomposition temperature of CF/PPS materials were determined using DSC and TGA instruments, and based on the operating parameters of the laser-assisted winding equipment, the process parameter range for this fabrication technology was designed. A numerical model for the temperature of laser-heated CF/PPS prepreg was established, and based on the filament winding process setup, the heating temperature and tensile strength were simulated and tested. The effects of process parameters on the heating temperature of the prepreg and the tensile strength of NOL rings were then analyzed. The non-dominated sorting genetic algorithm (NSGA-II) was employed to globally optimize the process parameters, aiming to maximize winding rate and tensile strength. The results indicated that core mold temperature, winding rate, laser power, and their interactions significantly affected mechanical properties. The optimal settings were 90 °C, 418.6 mm/s, and 525 W, achieving a maximum tensile strength of 2571.51 MPa. This study provides valuable insights into enhancing the forming efficiency of CF/PPS-reinforced high-performance engineering thermoplastic composites. [ABSTRACT FROM AUTHOR]

In this work, a method for measuring tow angles in carbon fiber components, based on the use of a polarized camera, is analyzed from a metrological point of view. Carbon fibers alter the direction of the reflected light's electrical field, so that in each point of the surface of a composite piece, the angle of polarization of reflected light matches the fiber orientation. A statistical analysis of the angle of linear polarization (AoLP) in each pixel of each examined area allows to evaluate the average winding angle. An evaluation of the measurement uncertainty of the method on a cylinder obtained by a filament winding process is carried out, and the result appears adequate for the study of the distribution of angles along the surface of the piece, in order to optimize the process. [ABSTRACT FROM AUTHOR]

The elastic, plastic, and in-plane damage evolutions of a carbon-fiber-reinforced epoxy composite fabricated via filament winding were studied based on continuum damage mechanics. The specific voids and resin-rich region distributions depended on the material and manufacturing conditions. The damage evolutions were expressed by a unified curve, indicating that the continuum damage mechanics approach gave a robust prediction of the damage evolution, although the critical damage at the ultimate failure depended on the material and manufacturing conditions. The damage coupling parameters were also affected by these conditions, which changed the damage evolution behavior under simultaneous shear and transverse damage development situations. [ABSTRACT FROM AUTHOR]

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The implosion of underwater composite structures is a critical and complex engineering problem, necessitating high-strength, lightweight, and corrosion-resistant materials for deep-sea applications. This manuscript reviews the intricate failure mechanisms of composite structures, focusing on cylindrical structures under extreme underwater conditions. The recent Titan submersible implosion serves as a case study, highlighting the significance of rigorous design considerations. Key topics include material degradation, buckling instability, and material failure, with a detailed analysis of composite layup optimization and manufacturing processes such as filament winding and roll wrapping. The manuscript underscores the need for comprehensive testing, advanced simulation techniques, and monitoring system integration to ensure the safety and effectiveness of composite pressure hulls. Future research should focus on developing more accurate failure models, optimizing manufacturing processes, and enhancing material properties through innovations in composite science to realize the full potential of composite materials in deep-sea applications. [ABSTRACT FROM AUTHOR]

Hydrogen is one of the critical components to address global challenges such as climate change, environmental pollution and global warming. It is a renewable source of energy that has many advantages compared to other renewables. Even though it may not be a "silver bullet" solution for the polluted world, there is still a big expectation that it can solve some of the energy crisis and challenges in the transportation, domestic and industry sectors. This study reviews the latest advancements in materials science, especially in the composite materials used for energy storage/transportation tanks. Special attention is given to towpreg material structures as the most promising ones for hydrogen storage. Various types of storage vessels are reviewed with emphasis on the most advanced type IV and type V vessels for energy (hydrogen) storage. The manufacturing processes, mainly filament winding (FW) and automatic fiber placement (AFP), are reviewed with their pros and cons. The sustainability aspects for the most promising hydrogen technologies, limitations and future challenges are also discussed. [ABSTRACT FROM AUTHOR]

Composite pipe is preferred over metal and other materials for water supply, liquid chemical transport, and fuel and gas transport. This is because composite pipes are more corrosion resistant, have a high strength/density ratio, high stiffness/density ratio, and more durable than metal pipes. The properties of the composite pipes employed may differ based on the operating environment. Therefore, determining the properties of the composite pipe according to the working environment is extremely important for its lifespan. The thickness of the samples is increased in line with different needs (such as increased strength). Increasing the thickness of samples, especially those exposed to different environmental conditions, and investigating the changes that will occur in the physical and mechanical properties of the samples are another important situation. In this investigation, glass fiber (GFRP) reinforced epoxy composite pipes have been examined, which were manufactured using the filament winding method with different layers [±55°]. To determine their properties in different working environments, the GFRP composite pipes were subjected to hydrothermal aging in pure water at 80°C for several days (7, 14, 21, and 28). The changes in their mechanical properties under working conditions were determined through hoop tensile strength tests and low velocity impact tests applied at different energy levels. The experimental results show that the tangential stress values increased by 10.59% as the number of layers increased. As the aging time increased, the durability of the 6-layer composite pipe decreased by 17.69%. Furthermore, the ability of the aged pipes to withstand damage was evaluated, revealing that the aging process exacerbated the damage within the pipes. [ABSTRACT FROM AUTHOR]

In this study, the axial compressive stresses of hollow circular composite tubes were investigated. For this purpose, hollow circular composite tubes with various inner diameters (Ø12 and Ø13 millimeters), a height of 80 millimeters, and an outer diameter kept constant at Ø17 millimeters were fabricated using a fiber winding process. In the production of hollow circular tubes, epoxy was used as resin, and glass fiber, carbon fiber, and Kevlar fiber were used as reinforcement materials. Experimental investigations were carried out for three different reinforcement materials, two thin-wall thicknesses, and five orientation angles. Axial compression tests were performed to research the influences of reinforcement materials, thin-wall thickness, and orientation angles on the compressive stresses. The axial compressive strength of the samples was observed experimentally by applying the load in the vertical direction. The reinforcement material, orientation angle, and thin-walled thickness had an important influence on the axial compressive stress. The glass/epoxy reinforcement material was found to have the highest axial compressive strength at 204 Mpa. When the orientation angle increased from 45° to 88°, the axial compressive stress increased by 2.27 times in glass/epoxy, 2.36 times in carbon/epoxy, and 2.37 times in Kevlar/epoxy specimens, respectively. In addition, by increasing the specimen wall thickness by 0.5 millimeters, the axial compressive stress at an 88° orientation angle increased by 9.67 % glass/epoxy, 11.85 % carbon/epoxy, and 7.14 % Kevlar/epoxy specimens. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the failure mechanisms of the filament-wound composite tubes under axial compressional loading by using an acoustic emission approach. First, the mechanical properties of ±45°C composite tubes were obtained experimentally. Then, failure due to the buckling phenomenon and crashworthiness characteristics were studied utilizing numerical simulation and experimental methods. Tubes were next simulated in ABAQUS software, and a continuum damage mechanics model was implemented in a progressive framework to assess the failure modes. From the macroscale view, results showed that the damage behavior of composite tubes turned out to be dominated by local buckling followed by a post-buckling field, which is generated by longitudinal cracks along the winding direction. On the micro-scale, the acoustic emission-based procedure based on the wavelet packet transform method was adopted. The hierarchical modeled assessment resulted in the identity of four clusters of AE signals. In GFRP tubes, the fiber breakage and fiber/matrix separation could mostly control the higher percentage of damage and cause to increase the energy absorption. Finally, by comparing the results obtained from micro and macro scales, the local buckling failure mode was attributed to the low content of fiber/matrix debonding in the structure. [ABSTRACT FROM AUTHOR]

The present paper investigates the suitability of a vitrimeric epoxy resin for processing in the wet filament winding (WFW) process to manufacture fiber‐reinforced polymers (FRP). Comprehensive material characterization of a commercially available epoxy and vitrimeric resin based on disulfide exchange is carried out, and the processing in WFW is evaluated by analyzing thermomechanical, rheological, thermochemical properties, and chemical shrinkage. The direct comparison of a vitrimer and an established epoxy resin permits an indication of the processability and necessary adjustments in WFW. Based on the implications of modeling, we demonstrate the processing of the vitrimeric resin in the WFW process by increasing the resin bath temperatures. The vitrimer's and conventional resin's elastic modulus development and compression behavior were similar, highlighting the vitrimeric resin's potential. Further, the results confirm that established characterization and modeling routines can be transferred to vitrimeric resins and, therefore, path the way toward advanced process simulation of vitrimeric resin's processing. For this, the present publication gives essential advice for setting up testing schedules for characterizing epoxy vitrimers' processing behavior and their appropriate modeling. The present work underlines the potential of applying commercially available dynamic hardeners to manufacture recyclable and malleable FRP in established processes. Highlights: Material characterization and modeling of wet filament winding process.Wet filament winding of epoxy vitrimers.Thermomechanical and chemical shrinkage characterization of epoxy vitrimers.Rheological and kinetic modeling of epoxy vitrimer. [ABSTRACT FROM AUTHOR]

This paper describes design, manufacture, and testing of a linerless composite vessel for liquid hydrogen, having 0.3 m diameter and 0.9 m length. The vessel consists of a composite cylinder manufactured by wet filament winding of thin-ply composite bands, bonded to titanium end caps produced by additive manufacturing. The aim was to demonstrate the linerless design concept with a thin-ply composite for the cylinder. The investigation is limited to the internal pressure vessel, while real cryogenic tanks also involve an outer vessel containing vacuum for thermal insulation. Thermal stresses dominate during normal operation (4 bar) and the layup was selected for equal hoop strains in the composite cylinder and end caps during filling with liquid hydrogen. Two vessels were tested in 20 cycles, by filling and emptying with liquid nitrogen to 4 bar, without signs of damage or leakage. Subsequently, one vessel was tested until burst at almost 30 bar. [ABSTRACT FROM AUTHOR]

Carbon fiber composites are known for excellent specific mechanical properties at room temperature. It is important to model the effect of temperature on flexural strength and interlaminar shear strength (ILSS). In this study, T700 carbon fiber composites with two different epoxy resins (Epofine, LY556) were prepared using filament winding and named as TE and TL composites. The dynamic mechanical analysis (DMA) tests revealed Tg of 177 and 192°C for TE and TL composites, respectively. Three‐point bending (flexural) and short‐beam shear (ILSS) tests were performed at −20, 0, RT, 90, 105, 150, 170, and 200°C. It was observed that flexural strength and ILSS decreases linearly with increase in temperature. Fracture analysis of flexural samples revealed fiber breakage at −20°C and micro‐buckling at elevated temperature are dominant failure mechanisms. Fracture analysis of ILSS samples showed delamination with microcracking at −20°C and plastic deformation of matrix at elevated temperature. A new empirical model was proposed to predict the temperature dependent flexural strength and ILSS. With this model, variation of flexure strength and ILSS with temperature can be estimated from respective values at RT, Tg and storage modulus values from DMA, thus extensive experimentation at high temperatures can be avoided. Highlights: Mechanical properties of filament wound composites are tested from −20 to 200°C.Flexural strength and ILSS linearly decreases with increase in temperature.Fiber breakage at −20°C and micro bucking at 200°C are dominant in flexure.Delamination at −20°C and plastic deformation at 200°C are dominant in ILSS.Analytical model for finding temperature dependent flexural strength and ILSS. [ABSTRACT FROM AUTHOR]

Translation abstract Novel 3D Reinforcements for Concrete Structures – Part 1: Background, Development, and PotentialFacing the challenges in the construction industry, especially the pursuit of sustainability and material efficiency, this article explores the development and potential of an innovative three‐dimensional (3D) and fully automated carbon fiber reinforcement structure, known as “Mesh”. This advanced method of reinforcement offers a versatile and resource‐efficient alternative to conventional steel reinforcement and an expansion of currently used carbon grids/elements. The Mesh is characterized by its adaptability to various shapes and load paths, significantly reducing the need for concrete and reinforcement, thereby enhancing the longevity and ecological footprint of construction projects. The development of the Mesh, from initial exploratory tests to its current status, as well as possible applications, including its potential as shear, surface, split tension, or helical reinforcement, especially in prestressed components, are discussed. This contribution highlights the Mesh′s contribution to the advancement of reinforcement technology in concrete construction and is part 1 of a multi‐part publication series. [ABSTRACT FROM AUTHOR]

By analyzing the failure mechanisms, crashworthiness characteristics of FW composite tubes subjected to two modes of progressive damage and catastrophic failure are investigated using acoustic emission technique and numerical method. The AE signals of ±45° composite tubes were classified using hierarchical and wavelet transform methods, and based on the realistic and three-dimensional geometrical architecture of tubular structures, the microstructural finite element model was developed using Catia and ABAQUS software. Then deformation patterns and the impression of each mechanism on the crashworthiness characteristics were assessed. Results indicated that fiber breakage and fiber/matrix debonding could likely control the higher percentage of damage. By changing the type of modes from progressive damage to catastrophic failure, the percentage of matrix cracking increases, the fiber/matrix separation decreases, and the failure behavior become dominated by local buckling. Comparing the FE simulation with experimental results, we found the proposed 3D model can reasonably predict the pre-crushing, post-crushing, and material densification. [ABSTRACT FROM AUTHOR]

In the field of textile technology, this study centers on towpreg—an integral component utilized in production techniques like tape laying and filament winding. Here, fibers are pre‐coated with resin, typically epoxy but not exclusively. Notably, towpreg retains a partially cured state, maintaining tackiness throughout the processing stages. The ultimate quality of the product manufactured with this towpreg is highly dependent on this initial material. This research highlights the importance of considering various factors that impact product quality. While not exhaustive, a systematic analysis of diverse towpreg parameters, including tack, resin content, and width, is provided. The work encompasses findings, challenges, and insights derived from towpreg manufacturing, incorporating the investigation of various experimental methodologies. The study also evaluates methodologies for laminated coupon production with towpreg, assessing their applicability in characterizing filament‐wound components. Although the article seems like a review, the authors aim to give a clear and holistic picture in one work instead of spreading information across many articles. Highlights: Techniques for the quantification of towpreg tack are presented.Resin content distribution along towpreg length is presented.Towpreg width variation was investigated, seen to be one of the major causes for the gaps and voids in a filament wound composite.Coupon‐level characterization of towpreg through filament winding approach is presented.Other filament winding parameters influencing the quality of the manufactured composite are discussed. [ABSTRACT FROM AUTHOR]

PyMAPDL, which stands for Python based Mechanical Ansys Parametric Design Language, provides a Pythonic interface to Ansys for automating tasks and managing multiple simulations. The present study focuses on utilizing PyMAPDL to numerically explore the stress and deformation conditions in the domed section of a cylindrical liner, specifically by analyzing ellipsoidal and torispherical dome shapes through the creation of a parametric model in Python. The output suggests a better selection of the dome geometrical parameters. The study extends to filament-wound composite pressure vessels, emphasizing the challenges in determining winding angles and layer thickness variations along the meridian line in dome parts. Cadfil software is used to obtain the thickness and angle variation of the composite layers, and the output data from Cadfil is imported into Ansys ACP as lookup table to generate the composite layer for linear elastic analysis of single composite layer on the liner. The findings suggest that a lower helical angle enhances strength protection in the dome section. • Utilization of Python via PyMAPDL (Python based Mechanical Ansys Parametric Design Language) for insightful analysis of dome geometrical parameters. • Ellipsoidal domes deform steadily until a radius-to-height ratio of 1.25, then stress and deformation rise. Torispherical domes require careful parameter selection for minimal deformation and stress; higher R k /R (knuckle radius to cylinder radius ratio) and lower R c /R (crown radius to cylinder radius ratio) ratios are preferable. • Cadfil software employed to determine composite layer thickness and angle variations, integrated into Ansys ACP for analysis. • Lower helical angles improve strength protection in dome sections. [ABSTRACT FROM AUTHOR]

In the present research work is demonstrated a cross-scale manufacturing approach for the production of multifunctional glass fiber reinforced polymer (GFRP) composite tubes with a purposely redesigned filament winding process. Up until now, limited studies have been reported towards the multiscale reinforcement direction of continuous fibers for the manufacturing of hierarchical composites at the industrial level. This study involved the development of two different multi-walled carbon nanotube (MWCNT) aqueous-based inks, which were employed for the modification of commercial glass fiber (GF) reinforcing tows via a bath coating unit in a pilot production line. The obtained multifunctional GFRP tubes presented a variety of characteristics in relation to their final mechanical, hydrothermal aging, electrical, thermal and thermoelectric properties. Results revealed that the two individual systems exhibited pronounced differences both in crushing behavior and durability performance. Interestingly, for lateral compression the MWCNT coatings comprising a polymeric dispersant minorly affected the mechanical response of the produced tubes. The crashworthiness indicators of the multifunctional tubes displayed a slight 5% variation to the respective reference values, combined with a more ductile behavior. Moreover, regarding the bulk electrical and thermal conductivity values, as well as the Seebeck coefficient factor, the corresponding tubes displayed a variance of 233% and 19% and an opposite semi-conducting sign denoting a p- and n-type character, respectively. [ABSTRACT FROM AUTHOR]

Carbon fiber resin-based composite materials are widely employed in the manufacturing of composite shells. During the curing process, the temperature gradients and cure degree gradients make it easy to generate thermal strains in both carbon fibers and resin, with the resin experiencing cure shrinkage strain due to the curing reaction, ultimately leading to residual stresses and strains. In this paper, a three-dimensional thermo–chemo–mechanical coupled curing model of the composite shell was established based on a resin test, and the changes of temperature, curing degree, residual stress, and strain during the solidification of the composite shell were investigated. First, the curing property parameters and elastic modulus of HCM-2184 resin were obtained through a curing dynamic test and a tensile test. Then, considering the heat release and shrinkage reaction of solidification, a coupled thermo–chemo–mechanical curing model was developed with the CHILE ( α ) elastic model, and the curing process of the composite shell was simulated numerically. The results show that the resin used in the test belongs to the autocatalytic reaction. For thin composite shells, the heat accumulation inside the shell during curing is not obvious. During the curing process, the curing shrinkage behavior of the resin is an important factor for the generation of residual stress and residual strain. [ABSTRACT FROM AUTHOR]

Composite pressure vessels and shells for aerospace applications demand enhanced structural performance with lesser inert mass. Optimum fiber tension during filament winding can significantly improve their structural performance; therefore, the fiber tension effect is studied on the carbon/epoxy composite specimen level. Fiber tension is varied from 0.5 to 6.0 kg during filament winding of composite specimens. Naval ordnance laboratory (NOL) ring and cylindrical shell specimens are made at different fiber tensions. The physical and mechanical properties of these specimens are investigated. Fiber volume fraction and hoop tensile strength of NOL ring specimens are increased by around 26% and 29%, respectively, at 4 kg fiber tension compared to 1 kg. The mass and thickness of the composite shells are reduced by around 19.5% and 24.5%, respectively, at 4 kg fiber tension compared to that of 1 kg. The experiment and result conclude an optimal fiber tension of 4 kg/ tow for efficient filament wound carbon/ epoxy composite specimen. [ABSTRACT FROM AUTHOR]

This study investigates a novel approach in modeling the system limits of a braked, high-speed yarn-laying process with in situ impregnation. Special attention is paid to the investigation of the yarn spool overrun after the robot has come to a standstill. This phenomenon occurs at low yarn tensions in combination with high traversing speed and/or acceleration. The modeling of the yarn spool overrun is carried out using physical equations, taking into account the travel speed, acceleration of the robot, and braking force of the spool brake. Previous research has confirmed various operating points of the yarn-laying process, but a comprehensive and complete analysis of the system limits at different operating points and speeds up to 2 m/s is missing. The result of the study is a novel model that describes the system boundaries of the direct-yarn-placement. Furthermore, models for robot braking time, carbon spool diameter, and spool mass are developed. The proposed models have an R 2 > 0.9674. Regarding the system stability boundaries, the calculations reveal that, as acceleration rises, the minimum tension requirement also increases. The same trend is found for system velocity. At a = 12.5 %, a minimum tension of 16 N suffices, compared to 23 N and 32 N at a = 25 % and 50%, respectively. The impact on tension of quadrupling the speed outweighs that of acceleration, with tension increasing by factors of up to 22.5 and 2, respectively. [ABSTRACT FROM AUTHOR]

Fiber-reinforced composites offer innovative solutions for architectural applications with high strength and low weight. Coreless filament winding extends industrial processes, reduces formwork, and allows for tailoring of fiber layups to specific requirements. A previously developed computational co-design framework for coreless filament winding is extended toward the integration of reciprocal design feedback to maximize design flexibility and inform design decisions throughout the process. A multi-scalar design representation is introduced, representing fiber structures at different levels of detail to generate feedback between computational design, engineering, and fabrication. Design methods for global, component, and material systems are outlined and feedback generation is explained. Structural and fabrication feedback are classified, and their integration is described in detail. This paper demonstrates how reciprocal feedback allows for co-evolution of domains of expertise and extends the existing co-design framework toward design problems. The developed methods are shown in two case studies at a global and component scale. [ABSTRACT FROM AUTHOR]

This study conducts a comparative analysis of glass fiber (GF) and jute fiber (JF) as energy-absorbing filament wound eco-friendly structures under quasi-static axial crushing with varying wall thickness, starting with a 2-layer configuration and progressing to 4 and 6 layers. Three primary failure modes, fiber-matrix fracturing, local buckling, and delamination were observed. Both JF and GF 2-layer configurations showed less progressive failure due to their lightweight nature, with crush force efficiency (CFE) of 0.44–0.46 and specific energy absorption (SEA) of 4.4–5.1 J/g, raising considerations for crash scenarios involving human safety. The 4-layer JF configuration demonstrated a significant increase in IPF to 3496 N, effectively restricting buckling and brittle fracture and leading to a higher SEA of 12.61 J/g. In comparison, the GF 4-layer configuration exhibits lower initial peak force (IPF) and SEA values but a higher CFE value of 0.64 at a lower weight of 58 g. The 6-layer JF configuration attains increased stability in load-bearing capacity with a CFE of 0.84 but at the cost of a high weight of 128 g. On the other hand, the 6-layer GF configuration showcases a higher SEA of 10.5 J/g with a moderate CFE of 0.75 and slightly lower weight, suggesting a delicate balance between performance and weight. Visual examination revealed dominant failure modes as local buckling in GF and brittle fracturing in JF configurations. Overall, the 4-layer configurations of JF and the 6-layer configuration of GF composite tubes demonstrate exceptional energy absorption efficiency, suggesting the potential for exploring hybrid configurations to achieve a balanced crashworthiness performance.

Composite structures, especially pressure vessels, pipelines, and additional components such as tees, reductions, or inspection openings are more and more willingly used in the chemical industry. In this research, a novel design of a low-pressure composite vessel with an inspection opening is presented. The vessels are unsymmetrical considering the domes. On one side the opening is considerably bigger, around half of the cylindrical diameter of the vessel. This design requires a new approach to manufacturing such structures. In this study, a two-step analysis was performed. Firstly, small-size pressure vessels (S) were manufactured and the design of dome reinforcement was validated. Then, the final design of vessel (M) was produced, with a volume of around 700 litres. The vessels were initially calculated for 21 bars of burst pressure. During burst pressure tests, the strains were measured with optical fibres (FBG) and strain gauges. Additionally, the acoustic emission was utilized to predict the damage modes and locations. Finally, a microscopic evaluation of the specific parts of the vessels was performed. Conclusions were drawn, that the proposed novel design of dome reinforcement around the inspection opening fulfilled the strength and stiffness requirements.

This study focuses on the measurement of frictional properties of towpregs applied in filament winding processes for carbon fiber reinforced plastic (CFRP) manufacturing. The filament winding technique is widely employed for creating rotationally symmetrical structures like pipes and pressure vessels due to its efficiency and cost-effectiveness. Accurate estimation of friction coefficients between towpregs and ­surfaces is crucial to ensure quality in wound components. Incorrect friction estimations can lead to suboptimal winding and compromised component performance. The study investigates various parameters influencing friction behavior, including fiber force and process speed. Experimental setups involve testing rovings under different conditions and measuring frictional forces. The results reveal, that increasing fiber forces and process speeds lead to higher friction forces. Comparative analysis with dry carbon fibers and other towpregs demonstrates varying friction behavior. The tests also showed a clear influence of the towpreg material aging on the friction coefficient. The static coefficient of friction values for different materials are calculated and discussed. This research contributes to a better understanding of friction phenomena in CFRP filament winding processes, aiding in optimizing manufacturing quality and efficiency.

Carbon nanotube (CNT) polymer composites have broad application prospects in thermal management as electrothermal heaters. Nevertheless, challenge remains in achieving high electrical conductivity for the composites due to the contradiction between CNTs and insulated polymers. To address this issue, herein, innovative use of interface strategy approach by constructing synergistic nanomaterial networks on carboxyl CNTs yarn winding composites for improving the interfacial adhesion and electrical performance. In the work, carboxyl CNTs yarn/CNTs‐graphene oxide (GO) polyvinyl alcohol (PVA) composites (C‐CY‐HP‐C) were proposed and manufactured via filament winding process. The as‐constructed C‐CY‐HP‐C demonstrated a remarkable interfacial shear strength of 2057.16 N mm−1, which was 53.59% higher than that of control CNTs yarn/PVA winding composites. In addition, the C‐CY‐HP‐C achieved an attractive electrical conductivity of 346.39 S cm−1 owing to the electronic transmission channels were formed. Notably, the superior electrical conductivity facilitated a rapid‐response of electrothermal performance for the C‐CY‐HP‐C. It reached a steady‐state temperature of 229.9°C within 10 s when the voltage was 1.2 V. Concurrently, it exhibited an impressive heating rate of 10.8°C min−1 at an ambient temperature of −20°C as the battery surface heater. These findings shed light on the development of technique for battery preheating system based on CNTs yarn/polymer composites. [ABSTRACT FROM AUTHOR]

In this paper, a novel hybrid manufacturing process that combines filament winding (FW) and tailored fiber placement (TFP) is introduced. The main idea is to place a TFP patch in between two filament wound layers aiming at maximizing the load transfer between the parts. To assess its feasibility, physical properties, such as density, fiber volume fraction and void content, and also the hybrid process kinematics and error propagation are evaluated. Furthermore, to determine the mechanical performance of this novel procedure, axial compression tests are carried out considering several unidirectional TFP patches. Key results show low-void content and good cross-section quality, demonstrating the feasibility of the process. In addition, mass–normalized load peaks as high as 394% with respect to the reference (non-patched) cylinder were obtained. [ABSTRACT FROM AUTHOR]

Previous studies on the design methods of filament winding paths for composite pressure vessels have mainly focused on geodesic and constant slippage coefficient non‐geodesic patterns, neglecting the design of variable slippage coefficients along the fiber path. In this paper, a design method of variable slippage coefficient non‐geodesic filament wound composite pressure vessels is proposed. The study begins by establishing a meridian rotation mapping model and deriving fiber path equations on the shell surface. Subsequently, the fiber paths, curvature characteristics, slippage coefficients, and shell stress responses of the shell under variable geometrical parameters are simulated and analyzed. Next, the winding parameters are optimized while considering bandwidth and stable winding constraints. The optimal winding parameters are determined, and filament winding simulations are conducted on composite pressure vessels. Results demonstrate the feasibility of the proposed method for variable slippage coefficient fiber path winding mode, providing a new and effective filament winding path design approach for composite pressure vessels. Highlights: Establishment of meridian rotation mapping model and simulation of shell fiber paths under variable geometric parameters.The fiber paths, curvature characteristics, slippage coefficients, and winding angles of the shell under variable geometrical parameters are simulated and analyzed.Stress response analysis of shells based on Tsai‐Wu failure criterion and classical lamination theory stress field dimensionless modeling.Construction of winding parameter optimization strategies and bandwidth error evaluation based on stable winding and fiber bandwidth constraints.Simulation of variable slippage coefficient non‐geodesic filament winding for composite pressure vessels with different parameters. [ABSTRACT FROM AUTHOR]

Carbon fiber/epoxy tow prepreg is an intermediate material for filament winding, consisting of fibers pre-impregnated with a matrix resin in a specific ratio. This study predicted the long-term viscoelastic properties of tow prepreg using DMA and TTSP. Typically, DMA involves applying a wound or laminated flat specimen, but a strand specimen was attempted to predict the characteristics of tow prepreg. The long-term viscoelastic properties were storage modulus, creep compliance, and relaxation modulus. Three test modes were performed in DMA to obtain each result. Smoothly overlapped master curves were obtained in all results. From the master curves, the viscoelastic properties of the material were predicted for 1 year, 10 years, and more extended periods. For 10 years, it was estimated that the storage modulus, creep compliance, and relaxation modulus changed by 7%, 132%, and 48%, respectively. When tests are conducted, considering future design variables, such as temperature, humidity, and out time, the results can be utilized to predict the long-term performance of tow prepreg and optimize composite manufacturing processes. [ABSTRACT FROM AUTHOR]

Technological advancements are exacting futuristic materials that exhibit comprehensive properties for diversiform applications. Cyanate Esters (CE) are promising materials that can suffice the current and future demands for myriad applications. This is possible because they exhibit multitudinal properties such as nominal density 1.17 g m 3 , high dimensional stability, low moisture absorption (0.5–2.5 wt%), high-temperature operating conditions (> 300 °C), low loss factor (tan δ = 10 - 3 to 6* 10 - 3 ), low dielectric constant k = 2.6 - 3.1 F m , EMI shielding, low defect density, strong wave permeability, thermo-mechanical and, chemical stability, excellent UV aging resistance, radiation resistance, excellent adhesion to conducting metals up to 250 °C, resistance to microcracks, glass transition temperature (240–290 °C), and good processability. CE's multifunctional properties paved the way for the exploitation as the matrix material in composites, an ideal thermoset for blending with various thermosets and thermoplastics resulting in phenomenal properties. CE is considered a desirable thermoset matrix for industrial applications due to its ability to meet the desired qualities, such as low cost, compatibility with conventional techniques, excellent shelf life, low curing temperature, high-temperature resistance, and low flammability. Moreover, CE-based composites and blends can be conveniently fabricated using existing techniques commonly employed for epoxy-based materials like resin transfer molding and filament winding, eliminating the need for developing new processing techniques. This review focuses on CE-based wave transparent composites, functionalization of fibers for better interfacial compatibility, shape memory polymers (SMP), EMI shielding effectiveness (EMI SE), and dielectric properties enhancement for various applications. [ABSTRACT FROM AUTHOR]

The accelerated testing methodology (ATM) developed by the authors is the methodology for predicting statistically long-term life of CFRP structures based on the viscoelasticity including the time-temperature superposition principle for matrix resin. The formulae of ATM are expressed as the product of static strength at room temperature, its dispersion, and the viscoelastic parameter of matrix resin that changes with time and temperature history. This methodology ATM was applied to the prediction of long-term creep failure life for unidirectional CFRP with heat-resistant epoxy resin as matrix under heat degradation in this study. Resin impregnated CFRP strands with heat-resistant epoxy resin were molded using a filament winding system as virgin specimens of unidirectional CFRP. Then, heat-degraded specimens were prepared by exposing the virgin specimens under acceleration conditions determined based on the time-temperature superposition principle for chemical deterioration assuming the condition of practical temperature 110°C and period 10 years. Second, the creep strengths of virgin and heat-degraded CFRP strands were statistically predicted based on ATM and the effect of heat degradation on the long-term life of CFRP strands was evaluated. As results, it was cleared that when the creep strength of CFRP strands undergoes thermal aging at the practical condition, in addition to the strength decrease to time due to the viscoelasticity of the resin, a comparable decrease in static strength and increase in this scatter occur. [ABSTRACT FROM AUTHOR]

Purpose: The effect of the stacking sequence and arrangement of layers in the use of carbon/epoxy and glass/epoxy are studied on the vibration behavior of a rotating hybrid composite shaft. Methods: In this paper, a hollow fiber-based hybrid composite shaft (HCS) with continuously extended fiber reinforcement consisting of carbon/epoxy and glass/epoxy layers with a symmetrical stacking sequence is modeled and built using the filament winding method. Strain potential energy is computed using Euler Bernoulli's theory and determining longitudinal stiffness, bending stiffness, torsional stiffness, and axial–torsional coupling. By using Hamilton's principle, the governing equations of motion are derived. The multiple scales method is used to obtain the approximate analytical answer of the HCS motion equations. Results: By solving the motion equations of the system, considering both the unbalanced mass of the shaft and disk, as well as the unbalanced mass of the shaft, natural frequencies are extracted for the 28-layer HCS with a centrally located disk and elastic bearings. The natural frequencies of analytical and numerical solutions of HCS with a centrally located disk and flexible supports are compared and validated. Then the natural frequencies of the non-rotating HCS are obtained using the modal analysis test and compared with the natural frequencies of the numerical solution, and the results are verified. The first three natural frequencies of the HCS with one disk supported by two elastic bearings are presented for various stacking sequences. Conclusions: The maximum natural frequencies of the rotating HCS with a disk positioned centrally on the shaft supported by two elastic bearings, occurred in an asymmetrical stacking sequence where eight layers of carbon/epoxy constituted the outermost layers of the HCS. Given the high torsional and bending stiffness of the carbon/epoxy, it is preferable to utilize it in the outer layers of the HCS. [ABSTRACT FROM AUTHOR]

Composite structures, especially pressure vessels, pipelines, and additional components such as tees, reductions, or inspection openings are more and more willingly used in the chemical industry. In this research, a novel design of a low-pressure composite vessel with an inspection opening is presented. The vessels are unsymmetrical considering the domes. On one side the opening is considerably bigger, around half of the cylindrical diameter of the vessel. This design requires a new approach to manufacturing such structures. In this study, a two-step analysis was performed. Firstly, small-size pressure vessels (S) were manufactured and the design of dome reinforcement was validated. Then, the final design of vessel (M) was produced, with a volume of around 700 litres. The vessels were initially calculated for 21 bars of burst pressure. During burst pressure tests, the strains were measured with optical fibres (FBG) and strain gauges. Additionally, the acoustic emission was utilized to predict the damage modes and locations. Finally, a microscopic evaluation of the specific parts of the vessels was performed. Conclusions were drawn, that the proposed novel design of dome reinforcement around the inspection opening fulfilled the strength and stiffness requirements. [ABSTRACT FROM AUTHOR]

The junction between cylindrical part and end dome is the most critical place of the filament wound composite pressure vessels because the shear forces and bending moments occur in this area. The strength analyses of junction between cylindrical part and different types of known end domes based on influence coefficients method were performed for filament wound composite pressure vessels manufactured using glass-epoxy and carbon-epoxy composites. Four known end domes were considered that is, a spherical shell, a geodesic-isotensoid shell, a shell based on minimizing of the Tsai-Hill's strength criterion and shell designed in authors' previous work (Hoffman 1 shell). Moreover, the study is also dealing with design of optimal end dome shape which takes account to the junction area. Finding of optimal end dome shape was based on data-driven evolutionary algorithms. Using input dataset from the analytical simulation surrogate models were created using Evolutionary Deep Neural Nets (EvoDN2) algorithm. The multicriterial optimization procedure was performed using Constrained Reference Vector Algorithm (cRVEA) optimization algorithm. Results indicates that the optimal end dome shape highly depend on material properties. [ABSTRACT FROM AUTHOR]

The reinforcing fibers in filament winding fiber-reinforced polymer (FFRP) are not arranged in the axial direction; thus, the members are vulnerable to bending and shear stresses. To address the limitations, this study evaluated FRP-concrete composite piles with reinforcing fiber arranged in circumferential directions. In particular, modular pultruded FRP (PFRP) members were fabricated with reinforcing fibers arranged in the axial and circumferential directions. The exterior of the fabricated PFRP members was reinforced with FFRP, and the flexural performance of these members was investigated through flexural strength tests. The results obtained from the flexural tests and flexural-stiffness prediction formula differed by approximately 0.72–1.36 times. A comparison between the results of the flexural test and flexural-strength prediction equation showed an error of approximately 1 to 10%. [ABSTRACT FROM AUTHOR]